The present invention relates to seals for use in fluid dynamic systems, and more particularly to a segmented seal assembly and method of retrofitting the same to turbines and the like.
Efficient operation of pressurized fluid systems, e.g., turbines, compressors and pumps, requires that high and low pressure operations be separate from one another. This is particularly true at the junctures of stationary and moving parts.
Many sealing systems have been developed for this purpose. Labyrinth seals, for example, use a segmented seal ring between moving blades of a rotating turbine shaft and a stationary turbine casing. The seal rings typically have a plurality of seal teeth for reducing the radial gap between the moving blades and casing to several thousandths of an inch. Some seal teeth extend radially inward and are spaced axially at intervals along the seal ring in opposition to the outer diameter of the shaft circumference. The objective is to effect a seal between the moving blades and the casing by restricting fluid flow between high and low pressure regions along the rotating shaft.
Upon failure of the seal, however, extensive machining may be required to replace it. In some cases, seal attachments are so weakened that replacement and maintenance of the seal are not feasible. The turbine unit must then operate without a complete set of seals, with reduced efficiency and at great expense to the operator. Given the unstable nature of worn or damaged seals, unit operation must be at reduced power levels in an effort to maintain reliable operation.